System of motor control.



No. 660,502. Patented Oct. 23, I900.

A. s. GARFIELD.

SYSTEM OF MOTOR CONTROL.

IApplicaticn fllad Mar. 11, 1899.)

Nb Model.)

WITNESSES- ARM @W,

UNITED STATES PATENT OEEIcE.

ALEXANDER S. GARFIELD, OF PARIS, FRANCE, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NEW YORK.

SYSTEM OF MOTOR CONTROL.

SPECIFICATION forming part of Letters Patent No. 660, 502, dated October 23,1900.

Application filed March 11,1899. Serial No. 708,653. (No model.)

0 (LU whom, it nutg concern:

Be it known that I, ALEXANDER S. GAR- FIELD, a citizen of the United States, residing at Paris, in the Republic of France, have i11- vented certain new and useful Improvements in Systems of Motor Control, (Case No. 946,) of which the following is a specification.

My present invention relates to systems of motor control. It is particularly adapted to those cases in which large and heavy trains are to be moved by a plurality of motor-cars, which may be interspersed throughout a train with cars provided with no motors or controlling apparatus. In addition to the motors and controllers upon each of these cars and in lieu of the master-controller which is sometimes employed in train systems I use signaling devices and have motormen stationed at the different controllers to operate them synchronously or as nearly so as may be desirable, so that substantially the same current and propelling power may be utilized and exerted by each of the sets of motors. It is manifest that it is immaterial how many of the cars there may be, and, further, that any desired number of motors may be employed upon each car. The character of the signaling device is also immaterial; but I have preferred for this an automatic arrangement which would indicate not only that a difference in current was present, but the extent of the difference, so that each rnotorman may intelligently manipulate his controller to bring the currents to equality, and thus prevent the shocks and jerks which would occur with motors using different currents. For this purpose I have preferred a differential am meter for each motor, with leads extending through the train. The ammeters are so connected that when the same current is flowing all of these, except the one connected to the first or leading car, will be at zero. I have used ammeters of the shunt type, as they are manifestly best adapted to the exercise of the invention; but other indicating devices might be used with good results, and their use I aim to cover by the claims appended.

The accompanying drawing is a diagram showing the invention as applied to a train of three cars. It is unnecessary to illustrate in full the different combinations of circuits which would be employed between the controllers and the motors, as these are so well understood in the art. I have therefore indicated all of the parts diagrammatically.

In the drawing, A indicates the supply-conductor extending along the track, and T T the traveling contacts furnishing current to the train-wire TV. The well-known thirdrail system is thus indicated, although of course any system involving making traveling connection could be substituted for it, or, in fact, any system whatever, so far as the present invention is concerned, which would s upply current at constant potential to a number of sets of motors. Nothing in the invention limits it to a train-control system, as for some purposes it may be very desirable to run motors located in different places with approximately the same current, and in this case the invention could be applied to stationary motors; but it is manifest that its greatest utility will be in the movement of railway-trains.

In the main trolley-lead for each car is a suitable controlling device K. This is inclicated in the drawing as a rheostat and is designed to vary the speed and torque of the motors from zero to maximum by any ap proved system of regulation. At R is the resistance of the amineter; There are two coils to each ammeter. On the first car the first coil AM is connected in shunt to the resistance R, which is in series with the motors M M between the trolley T and ground at G. Leads L L connect one of the coils in each ammeter upon the different cars in multiple with the resistance R. On the other cars the second or opposing coils AM of the am meters are connected to coil AM of the first indicator, a double-pole double-throw switch S being provided upon each car, by which the proper coil for the direction of motion of the train may be connected in. Of course the coil AMLin each case indicates the current supplied to its own set of motors.

The operation of the device is as follows: Then the train is started, the coil AM of the first differential am meter, connected in series with the first set of motors on the left of the train, indicates the current-flow in them, and the leads L L connect in multiple with this ammeter-coil the coils AM of all the others. lhis will displace the needles of the ammeters on the other cars; but when current is admitted to their motors by the manipulation of the controllers K t he needles will gradually return to their central position until when the current in the two coils AM AM of each ammeter is the same the needle will be at zero, thus indicating that the current-flow in each of the succeedingsets of motors equals that in the leading set. Of course in the first am meter the needle will be always displaced sufficiently to indicate current-flow.

Owing to the fact. that a number of the coils of the ammeters may be connected in multiple with the first of the resistances R, it is theoretically necessary to adjust that resistance in order to keep the calibration of the different instruments substantially similar, and I have therefore shown a switch for adjusting the shunt resistance of the first car. In practice, however, this will with all ordinary numbers of cars be unnecessary, the drop across the resistance-terminals being small and the resistance of the am meter-coils being so high that the current will divide between them in the ordinary way, the change in the ampere-turns of each coil being inconsiderable.

hat I claim as new, and desire to secure by Letters Patent of the United States, is-

1. In a system of motor control, the combination with a number of motors or sets of motors, and indicators near each motor or set of motors, one of said indicators being responsive only to current flowing in its adjacent motor or sets of motors, and another of said indicators responsive to current flowing in a non-adjacent motor or setof motors.

2. In an electric-railway system, the combination of a number of electrically-propelled cars, an indicator on one of the cars arranged to indicate only current flowingin circuits of said car, and an indicator on another car arranged to respond to flow of current in circuits of a car other than that on which it is placed.

3. In an electric-railway system, the combination of a number of cars each equipped with its own controller and a motor or motors regulated thereby, an indicator on one of the cars arranged to indicate only current How in a motor or motors on that car, and an indicator on another car arranged to be responsive to the [low of current in the motor or motors of a car other than that on which it is placed.

a. In an electricrailway system, the combination of a number of cars each equipped With its own controller and motors regulated thereby, of a differential ammeter upon each car, with some of its coils connected to indicate the current-flow in the motors upon that car, and the othercoils con nected to record the current-flow in other motors upon anot her car.

5. In an electric-railway system, the combination of motors and controllers therefor upon a number of cars, an ammeter for reg;- istering the current-flow in the leading car, and indicating devices upon the other cars in circuit With the ammeter and responsive to its indications.

6. The combination with a number of motor-cars, each provided with its own controller and motors regulated thereby, of a shunt-ammeter upon the leading car of the train indicating the current-flow in the motors thereof, and differential ammeters upon the other cars of the train, each of which has some of its coils connected in multiple to the calibrating-sh unt of the first-named am meter and its other coils serving to indicate the current-flow in the motors of the car upon which they are situated.

7. In an electric-railway system, the combination With a plurality of motor-ears in a single train, of motor-controllers, one upon each of said motor-cars; an indicator located near one motor-controller to be within the presence of the motorman operating the latter controller, means governed by another of said motor-controllers for operating said indicator, an indicator located near another motorcontroller, and means for cutting the latter indicator into or out of circuit.

In witness whereof I have hereunto set my hand this 8th day of March, 1899.

ALEXANDER S. GARFIELD.

Witnesses:

BENJAMIN B. HULL, MABEL E. JACOBSON. 

